#include <stdio.h>

int main() {
    int score;
    scanf("%d",&score);
    if (score >= 97 && score <= 100) printf("一甲");
    else if (score >= 92 && score <= 96) printf("一乙");
    else if (score >= 87 && score <= 91) printf("二甲");
    else if (score >= 80 && score <= 86) printf("二乙");
    else if (score >= 70 && score <= 79) printf("三甲");
    else if (score >= 60 && score <= 69) printf("三乙");
    else if (score <= 59) printf("无证书");
    printf("\n");
    return 0;
}
